• Refine Query
  • Source
  • Publication year
  • to
  • Language
  • 140
  • 13
  • 10
  • 10
  • 6
  • 2
  • 1
  • 1
  • Tagged with
  • 255
  • 255
  • 109
  • 85
  • 58
  • 57
  • 56
  • 54
  • 52
  • 35
  • 27
  • 26
  • 26
  • 25
  • 24
  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
71

Re-Engineering the alkanolamine absorption process to economize carbon capture

Warudkar, Sumedh 16 September 2013 (has links)
Climate change caused by carbon dioxide (CO2) released from the combustion of fossil fuels threatens to have a devastating impact on human life. Power plants that burn coal and natural gas to produce electricity generate more than half of global CO2 emissions. Separating the CO2 emitted at these large sources of emission, followed by long term storage has been proposed as short to medium term solution to mitigate climate change. Implementation of this strategy called 'Carbon Capture and Storage' would allow the continued use of fossil fuels while simultaneously reduce our CO2 emissions. Technologies such as the alkanolamine absorption process, used to separate CO2 from gas mixtures already exist. However, it is presently infeasible to use them for Carbon Capture and Storage due to their relatively large energy consumption. It is estimated that even with the use of state-of-the-art technology, the cost of electricity will increase by around 90%. The research presented in this dissertation is focused on developing novel strategies to limit the increase in the cost of electricity due to implementation of Carbon Capture and Storage. In order to achieve this objective, a process simulation software; ProMax® has been used to optimize the alkanolamine absorption process to suit Carbon Capture application. A wide range of process operating conditions has been analyzed for their effects on energy consumption. Included in this study are process conditions under which waste heat can be utilized for providing energy instead. Based on this analysis, some of the most energy efficient process configurations have been identified for an economic evaluation of their capital costs. This research has also led to the invention of novel absorbent blends which involve the replacement of water used in CO2 absorbents with alcohols. It has been shown that the use of these absorbents can significantly reduce energy consumption and thereby limit the increase in cost of electricity.
72

An Analysis of the Distribution and Economics of Oil Fields for Enhanced Oil Recovery-Carbon Capture and Storage

Hall, Kristyn Ann January 2012 (has links)
<p>The rising carbon dioxide emissions contributing to climate change has lead to the examination of potential ways to mitigate the environmental impact. One such method is through the geological sequestration of carbon (CCS). Although there are several different forms of geological sequestration (i.e. Saline Aquifers, Oil and Gas Reservoirs, Unminable Coal Seams) the current projects are just initiating the large scale-testing phase. The lead entry point into CCS projects is to combine the sequestration with enhanced oil recovery (EOR) due to the improved economic model as a result of the oil recovery and the pre-existing knowledge of the geological structures. The potential scope of CCS-EOR projects throughout the continental United States in terms of a systematic examination of individual reservoir storage potential has not been examined. Instead the majority of the research completed has centered on either estimating the total United States storage potential or the potential of a single specific reservoir.</p><p>The purpose of this paper is to examine the relationship between oil recovery, carbon dioxide storage and cost during CCS-EOR. The characteristics of the oil and gas reservoirs examined in this study from the Nehring Oil and Gas Database were used in the CCS-EOR model developed by Sean McCoy to estimate the lifting and storage costs of the different reservoirs throughout the continental United States. This allows for an examination of both technical and financial viability of CCS-EOR as an intermediate step for future CCS projects in other geological formations. </p><p>One option for mitigating climate change is to store industrial CO2 emissions in geologic reservoirs as part of a process known as carbon capture and storage (CCS). There is general consensus that large-scale deployment of CCS would best be initiated by combining geologic sequestration with enhanced oil recovery (EOR), which can use CO2 to improve production from declining oil fields. Revenues from the produced oil could help offset the current high costs of CCS. </p><p>The cumulative potential of CCS-EOR in the continental U.S. has been evaluated in terms of both CO2 storage capacity and additional oil production. This thesis examines the same potential, but on a reservoir-by-reservoir basis. Reservoir properties from the Nehring Oil and Gas Database are used as inputs to a CCS-EOR model developed by McCoy (YR) to estimate the storage capacity, oil production and CCS-EOR costs for over 10,000 oil reservoirs located throughout the continental United States. </p><p>We find that 86% of the reservoirs could store &#8804;1 y or CO2 emissions from a single 500 MW coal-fired power plant (i.e., 3 Mtons CO2). Less than 1% of the reservoirs, on the other hand, appear capable of storing &#8805;30 y of CO2 emissions from a 500 MW plan. But these larger reservoirs are also estimated to contain 48% of the predicted additional oil that could be produced through CCS-EOR. The McCoy model also predicts that the reservoirs will on average produce 4.5 bbl of oil for each ton of sequestered CO2, a ratio known as the utilization factor. This utilization factor is 1.5 times higher that arrived at by the U.S. Department of Energy, and leads to a cumulative production of oil for all the reservoirs examined of ~183 billion barrels along with a cumulative storage capacity of 41 Mtons CO2. This is equivalent to 26.5 y of current oil consumption by the nation, and 8.5 y of current coal plant emissions.</p> / Thesis
73

High-solids, mixed-matrix hollow fiber sorbents for CO₂ capture

Pandian Babu, Vinod Babu 08 June 2015 (has links)
Post-combustion carbon capture, wherein the CO2 produced as a result of coal combustion is trapped at the power plant exhaust, is seen as a bridging technology to reduce CO2 emissions and combat climate change. This capture process will however impose a parasitic load on the power plant and technologies need to be developed to minimize this energy penalty. This research focuses on a technology which uses solid sorbents fashioned into a hollow fiber form that allows water-moderated thermal cycling as a means of trapping CO2 from flue gas. While hollow fiber technology has intrinsic advantages over competing liquid amine and packed bed technologies, the materials used to fabricate hollow fibers and the fabrication process itself need to be optimized in order to result in competitive, robust hollow fiber sorbents. This dissertation focuses on the material selection process for each component of the hollow fiber platform and discusses ways to optimize the fiber and barrier layer formation. Different materials were evaluated to function as the solid sorbent, the matrix polymer and the barrier layer; and eventually their performance was measured against past work in this area.
74

Experimental analysis and modeling of perfluorocarbon transport in the vadose zone : implications for monitoring CO₂ leakage at CCS sites

Gawey, Marlo Rose 01 November 2013 (has links)
Perfluorocarbon tracers (PFTs) are commonly proposed tracers for use in carbon capture and sequestration (CCS) leak detection and vadose zone monitoring programs. Tracers are co-injected with supercritical CO₂ and monitored in the vadose zone to identify leakage and calculate leakage rates. These calculations assume PFTs exhibit “ideal” tracer behavior (i.e. do not sorb onto or react with porous media, partition into liquid phases or undergo decay). This assumption has been brought into question by lab and field evaluations showing PFT partitioning into soil contaminants and sorbing onto clay. The objective of this study is to identify substrates in which PFTs behave conservatively and quantify non-conservative behavior. PFT breakthrough curves are compared to those of a second, conservative tracer, sulfur hexafluoride (SF₆). Breakthrough curves are generated in 1D flow-through columns packed with 5 different substrates: silica beads, quartz sand, illite, organic-rich soil, and organic-poor soil. Constant flow rate of carrier gas, N₂, is maintained. A known mass of tracer is injected at the head of the columns and the effluent analyzed at regular intervals for tracers at picogram levels by gas chromatography. PFT is expected to behave conservatively with respect to SF₆ in silica beads or quartz sand and non-conservatively in columns with clay or organics. However, results demonstrate PFT retardation with respect to SF₆ in all media (retardation factor is 1.1 in silica beads and quartz sand, 2.5 in organic-rich soil, >20 in organic-poor soil, and >100 in illite). Retardation is most likely due to sorption onto clays and soil organic matter or condensation to the liquid phase. Sorption onto clays appears to be the most significant factor. Experimental data are consistent with an analytical advection/diffusion model. These results show that PFT retardation in the vadose zone has not been adequately considered for interpretation of PFT data for CCS monitoring. These results are preliminary and do not take into account more realistic vadose zone conditions such as the presence of water, in which PFTs are insoluble. Increased moisture content will likely decrease sorption onto porous media and retardation in the vadose zone may be less than determined in these experiments. / text
75

Using analytical and numerical modeling to assess deep groundwater monitoring parameters at carbon capture, utilization, and storage sites

Porse, Sean Laurids 09 April 2014 (has links)
Carbon Dioxide (CO₂) Enhanced Oil Recovery (EOR) is becoming an important bridge to commercialize geologic sequestration (GS) in order to help reduce anthropogenic CO₂ emissions. Current U.S. environmental regulations require operators to monitor operational and groundwater aquifer changes within permitted bounds, depending on the injection activity type. We view one goal of monitoring as maximizing the chances of detecting adverse fluid migration signals into overlying aquifers. To maximize these chances, it is important to: (1) understand the limitations of monitoring pressure versus geochemistry in deep aquifers (i.e., >450 m) using analytical and numerical models, (2) conduct sensitivity analyses of specific model parameters to support monitoring design conclusions, and (3) compare the breakthrough time (in years) for pressure and geochemistry signals. Pressure response was assessed using an analytical model, derived from Darcy's law, which solves for diffusivity in radial coordinates and the fluid migration rate. Aqueous geochemistry response was assessed using the numerical, single-phase, reactive solute transport program PHAST that solves the advection-reaction-dispersion equation for 2-D transport. The conceptual modeling domain for both approaches included a fault that allows vertical fluid migration and one monitoring well, completed through a series of alternating confining units and distinct (brine) aquifers overlying a depleted oil reservoir, as observed in the Texas Gulf Coast, USA. Physical and operational data, including lithology, formation hydraulic parameters, and water chemistry obtained from field samples were used as input data. Uncertainty evaluation was conducted with a Monte Carlo approach by sampling the fault width (normal distribution) via Latin Hypercube and the hydraulic conductivity of each formation from a beta distribution of field data. Each model ran for 100 realizations over a 100 year modeling period. Monitoring well location was varied spatially and vertically with respect to the fault to assess arrival times of pressure signals and changes in geochemical parameters. Results indicate that the pressure-based, subsurface monitoring system provided higher probabilities of fluid migration detection in all candidate monitoring formations, especially those closest (i.e., 1300 m depth) to the possible fluid migration source. For aqueous geochemistry monitoring, formations with higher permeabilities (i.e., greater than 4 x 10⁻¹³ m²) provided better spatial distributions of chemical changes, but these changes never preceded pressure signal breakthrough, and in some cases were delayed by decades when compared to pressure. Differences in signal breakthrough indicate that pressure monitoring is a better choice for early migration signal detection. However, both pressure and geochemical parameters should be considered as part of an integrated monitoring program on a site-specific basis, depending on regulatory requirements for longer term (i.e., >50 years) monitoring. By assessing the probability of fluid migration detection using these monitoring techniques at this field site, it may be possible to extrapolate the results (or observations) to other CCUS fields with different geological environments. / text
76

Är koldioxidavskiljning och lagring nödvändigt för att uppnå klimatmålen? : En översikt ur ett globalt, europeiskt och svenskt perspektiv. / Is carbon capture and storage necessary to achieve the climate goals? : An overview from a global, European and Swedish perspective

Rosell, Elias January 2015 (has links)
Koldioxidavskiljning och lagring (CCS) har lyfts fram som ett verktyg för att hejda klimatförändringarna. I detta arbete har det undersökts om CCS är nödvändigt för att uppnå klimatmålen på global, europeisk och svensk nivå. I uppsatsen, som är en litteraturstudie, har det även undersökts vilka möjligheter och risker som finns med att använda CCS och vilka förutsättningar som krävs för att CCS ska användas. Resultaten är att CCS är enligt en majoritet av forskningen nödvändigt för att uppnå tvågradersmålet och det anses även behövas för att EU:s klimatmål ska uppnås. Cirka 10 miljoner ton av de årliga svenska utsläppen runt år 2050 kan behöva lagras om Sverige ska vara klimatneutralt år 2050. Det finns tillräckliga geologiska kapacitet för koldioxidlagring i världen i helhet, Europa och Sverige. En intressant möjlighet med CCS är att ta ned koldioxid från atmosfären genom att lagra koldioxid från bioenergi. Avgörande för utvecklingen av CCS är att det finns ett pris på koldioxidutsläpp som gör det dyrare att släppa ut koldioxid än att lagra den. Det är sannolikt att 99 procent av den lagrade koldioxiden är kvar inom 1000 år. Fossilenergi med CCS är ur klimatsynpunkt betydligt bättre än fossilenergi utan CCS. Men CCS gör inte fossilenergi till ett problemfritt energislag. En nackdel är att CCS leder till mer kolbrytning. En slutsats är att mycket ändå talar för att riskerna med att inte använda CCS för att bekämpa den globala uppvärmningen är större än riskerna med CCS. / Carbon capture and storage (CCS) has been discussed as a possible tool to mitigate climate change. This study is investigating whether CCS is necessary to achieve climate goals at the global, European and Swedish levels. This study, which is a literature-review, has also looked into the possibilities, opportunities and risks linked to the use of CCS. The result is that CCS, according to the majority of the research, is necessary to achieve the “two degree target” and is also needed for achieving EU's climate goals.  By year 2050 Sweden may need to store approximately 10 million tons of emissions annually in order to become climate neutral. There is sufficient geological capacity for carbon storage in the world, where Europe and Sweden have the capacity to store their own emissions. An interesting possibility of CCS is to reduce carbon dioxide from the atmosphere by storing carbon from biomass. Crucial to the development of CCS is the need for a price on carbon dioxide that makes it more expensive to emit carbon dioxide than to store it. It is likely that 99 percent of the stored carbon dioxide is retained for at least 1000 years. Fossil fuels with CCS are from a climate point of view, considerably better than fossil energy without CCS. But CCS does not make fossil energy problem-free. It leads to more coal mining. A conclusion is that the risks of not using CCS to combat global warming are greater than the risks of using CCS.
77

Distribution of Oil and Gas Well Data Through a Web Based Map Application

Richards, Kenneth T. January 2013 (has links)
The Arizona Oil and Gas Commission in conjunction with the Arizona Geological Survey have collected a large amount of data for the oil and gas wells in the State of Arizona. The data covers over 1,000 wells that were drilled from the 1940s to present. This data includes copies of permits, location information, scanned copies of well logs and digitized versions of the well logs in .las file format. These files have been difficult to distribute efficiently because of an unfriendly web user interface. The purpose of this project is to give the Arizona Geological Survey a way to distribute the oil and gas well data through an effective web application. The web application will leverage existing web services at the Arizona Geological Survey. To create this map I used the Esri JavaScript API. In this application the users can select multiple wells by clicking and dragging over the well heads they want. This will then display the metadata in a grid along with hyperlinks to the available files for those wells. This data will be primarily used by companies involved with carbon sequestration or others seeking information for geological exploration.
78

Analytical Estimation of CO2 Storage Capacity in Depleted Oil and Gas Reservoirs Based on Thermodynamic State Functions

Valbuena Olivares, Ernesto 2011 December 1900 (has links)
Numerical simulation has been used, as common practice, to estimate the CO2 storage capacity of depleted reservoirs. However, this method is time consuming, expensive and requires detailed input data. This investigation proposes an analytical method to estimate the ultimate CO2 storage in depleted oil and gas reservoirs by implementing a volume constrained thermodynamic equation of state (EOS) using the reservoir?s average pressure and fluid composition. This method was implemented in an algorithm which allows fast and accurate estimations of final storage, which can be used to select target storage reservoirs, and design the injection scheme and surface facilities. Impurities such as nitrogen and carbon monoxide, usually contained in power plant flue gases, are considered in the injection stream and can be handled correctly in the proposed algorithm by using their thermodynamic properties into the EOS. Results from analytical method presented excellent agreement with those from reservoir simulation. Ultimate CO2 storage capacity was predicted with an average difference of 1.3%, molar basis, between analytical and numerical methods; average oil, gas, and water saturations were also matched. Additionally, the analytical algorithm performed several orders of magnitude faster than numerical simulation, with an average of 5 seconds per run.
79

Three applications of green chemistry in engineering: (1) silylamines as reversible ionic liquids for carbon dioxide capture; (2) carbon dioxide as protecting group in chemical syntheses; (3) mitigating the thermal degradation of polyvinyl chloride

Switzer, Jackson Reeves 27 August 2014 (has links)
Green chemistry principles served as a guide for three industrially-relevant projects. In the first project, silylamines were applied as reversible ionic liquids for carbon dioxide capture from post-combustion flue gas streams. The effect of silylamine structure was thoroughly researched to develop a comprehensive library of silylamines and an accompanying set of structure-property relationships. The proposed solvent systems have the potential to present significant energy savings, as design has focused on their use in a non-aqueous, solvent-free environment. The second project also dealt extensively with carbon dioxide capture, as a reversible, in-situ protecting group for amines. Three strategies for the reversible protection of amines using carbon dioxide were developed and evaluated. Further, a chemoselective reaction was performed using carbon dioxide to protect a reactive amine and consequentially direct reactivity elsewhere within the same molecule. The carbon dioxide-protection technology developed has significant impact in multi-step industrial syntheses, as reversible, in-situ protection with carbon dioxide could eliminate the need for separate protection and deprotection unit operations. Lastly, a study was performed on the thermal degradation and stabilization of PVC in the presence of both plasticizers and thermal stabilizers. The study combined both model compound experiments as well as work with bulk PVC blends to gain a holistic understanding of the processes that take place during the degradation and stabilization of PVC. A bio-based plasticizer was investigated as a replacement for petroleum-based phthalate plasticizers. Additionally, two novel thermal stabilizers for PVC were presented and evaluated.
80

Multiscale modeling of nanoporous materials for adsorptive separations

Kulkarni, Ambarish R. 12 January 2015 (has links)
The detrimental effects of rising CO₂ levels on the global climate have made carbon abatement technologies one of the most widely researched areas of recent times. In this thesis, we first present a techno-economic analysis of a novel approach to directly capture CO₂ from air (Air Capture) using highly selective adsorbents. Our process modeling calculations suggest that the monetary cost of Air Capture can be reduced significantly by identifying adsorbents that have high capacities and optimum heats of adsorption. The search for the best performing material is not limited to Air Capture, but is generally applicable for any adsorption-based separation. Recently, a new class of nanoporous materials, Metal-Organic Frameworks (MOFs), have been widely studied using both experimental and computational techniques. In this thesis, we use a combined quantum chemistry and classical simulations approach to predict macroscopic properties of MOFs. Specifically, we describe a systematic procedure for developing classical force fields that accurately represent hydrocarbon interactions with the MIL-series of MOFs using Density Functional Theory (DFT) calculations. We show that this force field development technique is easily extended for screening a large number of complex open metal site MOFs for various olefin/paraffin separations. Finally, we demonstrate the capability of DFT for predicting MOF topologies by studying the effect of ligand functionalization during CuBTC synthesis. This thesis highlights the versatility and opportunities of using multiscale modeling approach that combines process modeling, classical simulations and quantum chemistry calculations to study nanoporous materials for adsorptive separations.

Page generated in 0.0607 seconds